On the one hand, pistons are widely known and used in internal combustion motors. The motors often operate with a frequency of several thousands rotations per minute at elevated temperatures. A lot of attention has been given to the working of those pistons, and more particularly to the reduction of friction of the piston inside the cylinder bore. Incremental reductions in friction or incremental improvements in lubrication may increase substantially the efficiency of the motor.
On the other hand, coatings such as diamond-like coatings are well known in the art, amongst others, for their hardness, for their corrosion resistance and for their low coefficient of friction. Diamond-like coatings have been applied successfully on various automotive components such as valve heads, rods, shafts, piston rings, and cylinder head.
Despite the widely spread use of pistons of internal combustion motors and despite the existence of hard coatings such as diamond-like coatings, application of hard coatings such as diamond-like coatings to the skirts of pistons has proved to be unsuccessful and not in line with other applications of diamond-like coatings.